721281 has 12 divisors (see below), whose sum is σ = 1057616. Its totient is φ = 436920.

The previous prime is 721267. The next prime is 721283. The reversal of 721281 is 182127.

It is not a de Polignac number, because 721281 - 2¹⁰ = 720257 is a prime.

It is a super-3 number, since 3×721281³ = 1125731273333493123, which contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721283) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 631 + ... + 1356.

2⁷²¹²⁸¹ is an apocalyptic number.

It is an amenable number.

721281 is a deficient number, since it is larger than the sum of its proper divisors (336335).

721281 is a wasteful number, since it uses less digits than its factorization.

721281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2012 (or 2001 counting only the distinct ones).

The product of its digits is 224, while the sum is 21.

The square root of 721281 is about 849.2826384661. The cubic root of 721281 is about 89.6812178784.

The spelling of 721281 in words is "seven hundred twenty-one thousand, two hundred eighty-one".